Citing South Korea's presidential Blue House, various local news outlets reported that Moon gave Kim a book and a USB drive containing an e-book and a presentation on the "New Economic Map of the Korean Peninsula," something Moon announced last year.

The map is a blueprint for economic cooperation between North Korea and South Korea and includes three "belts": one along the eastern coast and Russian border for energy and resources, another along the western coast for transportation and logistics, and a third across the land border for tourism.

Moon most likely wants to use the map — which also outlines gas pipes and an inter-Korean train network that could connect with China, Russia, and Europe — to entice North Korea to keep to the Panmunjom Declaration signed at the demilitarized zone.

The purpose of giving Kim the flash drive appears to be an attempt to convince Kim that North Korea needs international economic support after years of sanctions.

"The USB makes the case to Kim — there really is another path for you," John Delury, a North Korea expert at Yonsei University, told the news website Axios.

Delury told Axios that the flash drive would send a message to Kim: "We're serious about working with you for what we think is your real ambition, to be a wealthy East Asian country."

USB drives are frequently smuggled into North Korea with content banned in the country, including South Korean and Hollywood films, as well as global news. Many people who have defected from North Korea have said the foreign content on these flash drives played a part in their decision.

Defector groups often send USB drives — along with mini radios, flyers, and $1 bills — in balloons across the border, though police in South Korea blocked a planned release of flyers on Saturday.